Direction of the magnetization of thin films and sandwiches as a function of temperature

Abstract

We present a simple model for the temperature and thickness dependence of the direction of magnetization of ferromagnetic thin films or sandwiches. Above a temperature that is much smaller than the Curie temperature, the magnetization in the presence of a uniaxial anisotropy is aligned completely parallel to the surface plane. The main reason for this is the entropy of the magnetization vector. Also, the direction of magnetization is determined by the competition between uniaxial and shape anisotropy. The decrease of the magnetic ordering for increasing temperature turns out to be not so important.